Many methods for obtaining a positive color image by a diffusion transfer process have been proposed.
For example, U.S. Pat. Nos. 4,559,290, 4,356,249 and 4,358,525, JP-A-53-35533 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A 53-110827, JP-A-54-130927, JP-A-56-164342, JP-A-59-154445 and JP-A-62-215270 disclose methods wherein dye-providing compounds which are oxidation type compounds incapable of releasing any dye are allowed to coexist with reducing agents or precursors thereof, the reducing agents are oxidized according to the exposure amount of silver halide by wet development or heat development, and reduction is carried out by the reducing agents which are left behind without being oxidized to release diffusible dyes. Further, EP-A-220746 and Kokai Giho 87-6199 (Vol. 12, No. 22) disclose color light-sensitive materials containing non-diffusible compounds which release diffusible dyes by the reductive cleavage of an N-X bond (wherein X is an oxygen, a nitrogen or a sulfur atom).
However, when the reducible dye-providing compounds together with the reducing agents or precursors thereof are used in combination with silver halide emulsions, problems occur in that the dye image is highly stained and raw stock-preservability is poor.
The use of diffusible electron transferring agents in addition to non-diffusible electron donors as reducing agents is effective in preventing a positive image from being stained in light-sensitive materials for forming a positive image containing reducible dye-providing compounds. However, the electron transferring agent radicals formed are diffused in other layers having different color sensitivity, and the electron donors contained in the layers are cross-oxidized by the radicals. Therefore, image density is lowered and color reproduction is deteriorated. Attempts have been made to provide an intermediate layer between light-sensitive layers having different color sensitivity from each other, or to incorporate a reducing substance in the intermediate layer. However, the amounts of binder and reducing substance to be added to each layer are limited to a certain range from the viewpoints of image-forming rate, resolution, layer quality, etc. in diffusion transfer type light-sensitive materials a in the present invention. Accordingly, a further improvement is demanded.